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Diurnal evaporative testing of atmospheric fuel system with no-load canister for 14 days and half load canister for 7 days is carried out according to the US EPA BETP test procedure. In addition, the atmospheric fuel system and pressurized fuel system were tested for BETP for 72h diurnal evapration respectively.The results show that the total emissions of the atmospheric fuel system in 72h is 210mg, and the proportion of respiratory emissions is between 90% - 95%. The 72h total emissions of the pressurized fuel system is about 120mg, and the permeation emissions of the fuel tank accounts for about 82% - 90%. The total respiratory emissions of the atmospheric fuel system are 130.4 mg, mainly alkanes, accounting for 70% - 80%. The pressurized fuel system is dominated by the permeation emission of the fuel tank, with a total amount of 127.5 mg, mainly composed of alkanes, aromatic hydrocarbons and OVOCs, accounting for 45% - 50%, 43% - 47% and 3% - 5% respectively.

Two vehicles with ORVR system which are met with the US standard were studied. A comparative of refueling emissions test under different refueling rate and different refueling temperature were studied. The HC chemical analysis was carried out for the fuel gas emission from a sample car. The results show that with the increase of the refueling rates, the refueling emissions decline at first, and then gradually stabilize; with the increase of the refueling temperature, the results of refueling emissions show a gradual increase. Under the condition of 37 L / min refueling flow rate and 20 °C fuel temperature, 14 kinds of alkanes are emitted from the fuel, in which isobutane, isopentane and n-pentane are the highest emissive components, accounting for 57.66% of the total amount of VOCs.

A filler pipe of vehicle fuel tank has been simulated and optimized about refueling smoothness which is based on On-board Refueling Vapor Recovery (ORVR). Both liner of filler pipe and straight pipe section at the bottom of filler pipe have been studied. The results show that extending the end of the liner to the first elbow of the filler pipe can effectively control the phenomenon of fuel spit-back in the refueling process and promote the refueling process to be smoother. Compared with the bottom of the original filler pipe, extending the bottom length to 100 mm, adding the upper open form in check valve structure, the result shows that in the process of refueling, dynamic fluid sealing can be formed to meet the design requirements. After that, the fuel system bench test was carried out, and conducted a bench test to verify the simulation results.

In order to study the single cavity and double cavity canister work performance, the L/D, as well as the similarities and differences among the diameter of the adsorption mouth, purge mouth and air mouth have been studied. At the same time, the work performance of ORVR canister and common canister is also studied. The results demonstrate that the similar of L/D, efficient work ability and efficient adsorption rate of the double cavity canister is better than the single cavity canister. The bigger of L/D, the stronger work ability of the canister. However, the excessive increase of the L/D is not conducive to the canister desorption, instead resulting in the increase of RARCP. The adsorption mouth diameter of common canister is generally smaller or similar to the purge mouth, while for ORVR canister the adsorption mouth diameter is bigger than the purge mouth and similar to air mouth.